General procedure for the synthesis of 1-pyrenylbutyric acid from 4-oxo-4-(pyren-1-yl)butyric acid: 1 g (2.78 mmol) of 4-oxo-4-(pyren-1-yl)butyric acid was dissolved in 30 mL of diethylene glycol, to which were added 0.59 g (10 mmol) of hydrazine hydrate and 0.56 g (10 mmol) of KOH.The reaction mixture was heated and refluxed for 2 h. The reaction mixture was subsequently poured into ice hydrochloric acid (25%) to produce a yellow precipitate. The solid was collected by filtration and recrystallized from ethanol to give 570 mg (71% yield) of 4-(pyrene-1-yl)butanoic acid. Molecular formula C20H16O2, molecular weight 288 g/mol. EI-MS: m/z (%) = 289 (16) [MH+], 288 (62) [M], 216 (20), 215 (100), 213 (11). High-resolution EI-MS (C20H16O2): calculated value 288.1150; measured value 288.1150.1H-NMR ([D6]-DMSO): δ (ppm) = 8.50-7.92 (9H, m, CHarom), 3.36 (2H, m, CH2C16H9), 2.41 (2H, m, CH2CO2H), 2.04 (2H, m, CH2CO2H), 2.04 (2H, m, CH2CO2H). 2.04 (2H, m, CH2).1H-NMR (CDCl3): δ (ppm) = 8.32-7.86 (9H, m, CHarom), 3.42 (2H, t, CH2C16H9, 3JHH = 7.57 Hz), 2.51 (2H, t, CH2CO2H, 3JHH = 7.00 Hz), 2.23 (2H, m, CH2, 3JHH = 7.00 Hz), 2.23 (2H, m, CH2, 3JHH = 3JHH). m, CH2, 3JHH = 7.57Hz, 3JHH = 7.00Hz).13C-NMR ([D6]-DMSO): δ (ppm) = 174.74 (1CO), 136.39-123.39 (9 CHarom, 7 Carom), 33.64-26.98 (1CH2CO2H, 2CH2).13C- NMR (CDCl3): δ (ppm) = 177.48 (1CO), 135.25-123.04 (9 CHarom, 7 Carom), 33.21-26.46 (1CH2CO2H, 2CH2).IR (KBr): ν (cm-1) = 3447w, 3037w, 2950m, 2934w, 2874w, 1695s, ν (cm-1) 2874w, 1695s, 1431w, 1275m, 1206m, 918w, 846s, 711w.